Merged FrameBuffer3 {Next,Last}DecodableTemporalUnitRtpTimestamp() function.

Bug: webrtc:13343
Change-Id: Ic21eddd38466e6b5fd8b912b3ee2d9dc47a0ba35
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/260981
Reviewed-by: Evan Shrubsole <eshr@webrtc.org>
Reviewed-by: Erik Språng <sprang@webrtc.org>
Commit-Queue: Philip Eliasson <philipel@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#36756}
diff --git a/modules/video_coding/frame_buffer3.h b/modules/video_coding/frame_buffer3.h
index 5bcfbd2..aef26d4 100644
--- a/modules/video_coding/frame_buffer3.h
+++ b/modules/video_coding/frame_buffer3.h
@@ -31,6 +31,11 @@
 // The FrameBuffer is thread-unsafe.
 class FrameBuffer {
  public:
+  struct DecodabilityInfo {
+    uint32_t next_rtp_timestamp;
+    uint32_t last_rtp_timestamp;
+  };
+
   // The `max_size` determines the maxmimum number of frames the buffer will
   // store, and max_decode_history determines how far back (by frame ID) the
   // buffer will store if a frame was decoded or not.
@@ -56,8 +61,7 @@
 
   absl::optional<int64_t> LastContinuousFrameId() const;
   absl::optional<int64_t> LastContinuousTemporalUnitFrameId() const;
-  absl::optional<uint32_t> NextDecodableTemporalUnitRtpTimestamp() const;
-  absl::optional<uint32_t> LastDecodableTemporalUnitRtpTimestamp() const;
+  absl::optional<DecodabilityInfo> DecodableTemporalUnitsInfo() const;
 
   int GetTotalNumberOfContinuousTemporalUnits() const;
   int GetTotalNumberOfDroppedFrames() const;
@@ -87,7 +91,7 @@
   const size_t max_size_;
   FrameMap frames_;
   absl::optional<TemporalUnit> next_decodable_temporal_unit_;
-  absl::optional<uint32_t> last_decodable_temporal_unit_timestamp_;
+  absl::optional<DecodabilityInfo> decodable_temporal_units_info_;
   absl::optional<int64_t> last_continuous_frame_id_;
   absl::optional<int64_t> last_continuous_temporal_unit_frame_id_;
   video_coding::DecodedFramesHistory decoded_frame_history_;